This invention concerns a high pressure rubber hose and a manufacturing method thereof and, more specifically, it relates to a high pressure rubber hose intended for the improvement of flexibility and the reduction of weight by using organic fibers and steel wires together as a reinforcing material while preventing breakage of organic fibers caused by buckling, as well as a manufacturing method thereof.
High pressure rubber hoses include those having plural reinforced layers each buried by way of an intermediate rubber layer between an inner rubber layer and an outer rubber layer and spirally braiding steel wires as a reinforced layer. However, the steel wire reinforced layer involves drawbacks of poor flexibility and remarkable increase in the weight of the hose. Then, for the improvement of the flexibility and the reduction of the weight, it has been attempted to replace a portion of the reinforced layer with organic fibers such as aromatic polyamide fibers.
However, since the organic fibers of high modulus of elasticity used for reinforcement such as aromatic polyamide fibers are tended to be broken by buckling, they have a problem of poor durability as the reinforcing material for the high pressure rubber hose. Therefore, it has been generally considered difficult to obtain a high pressure rubber hose reduced in the weight and excellent in the flexibility by the combined use of the organic fiber material and the steel wire material.
This invention intends to provide a high pressure rubber hose for the improvement of the flexibility and the reduction of the weight by combined use of organic fibers and steel wires as a reinforcing material, and for the improvement of the durability by preventing breakage of organic fibers caused by buckling, as well as a manufacturing method thereof.
A high pressure rubber hose according to this invention for attaining the foregoing object resides in a high pressure rubber hose having plural reinforced layers each buried by way of an intermediate between an inner rubber layer and an outer rubber layer, in which an organic fiber reinforced layer braided from organic fiber cords into two spiral layers or one braid-like layer is disposed to the inner rubber layer on the outer circumference thereof, a steel wire reinforced layer braided from steel wires into two spiral layers is disposed to the organic fiber reinforced layer at the outer circumference thereof, wherein the braiding angle of the organic fiber reinforced layer is less than the braiding angle of the steel wire reinforced layer and the braiding tension of the organic fiber reinforced layer is higher than the braiding tension of the steel wire reinforced layer.
In a case of using the organic fibers and the steel wires in combination as the reinforcing material for the high pressure rubber hose for improving the flexibility and reducing the weight as described above, since the braiding angle of the organic fiber reinforced layer is less than the braiding angle of the steel wire reinforced layer and the braiding tension of the organic fiber reinforced layer is higher than the braiding tension of the steel wire reinforced layer, stress of the organic fiber reinforced layer undergoing from the steel wire reinforced layer (strain) is decreased to suppress buckling, so that breakage of the organic fibers by buckling can be prevented to improve the durability.
Meanwhile, a method of manufacturing a high pressure rubber hose according to this invention comprises molding an unvulcanized inner rubber layer on the outer circumference of an elongate flexible mandrel, forming an organic fiber reinforced layer braided from organic fiber cords into two spiral layers or one braid-like layer to the outer circumference thereof, forming a steel wire reinforced layer braided from steel wires into two spiral layers on the outer circumference thereof by way of an unvulcanized intermediate layer, laminating an unvulcanized outer rubber layer on the outer circumference thereof and then taking up the flexible mandrel around a drum and applying vulcanization.
According to the manufacturing method described above, a high pressure rubber hose having the organic fiber reinforced layer and the steel wire reinforced layer can be formed to a length of 40 m or more.